Torch ignitors with gas assist start

ABSTRACT

An embodiment of a torch ignitor system for combustor of a gas turbine engine includes a torch ignitor, the torch ignitor having a combustion chamber oriented about an axis, the combustion chamber having axially upstream and downstream ends defining a flow direction through the combustion chamber, along the axis. The torch ignitor system also includes a cap defining the axially upstream end of the combustion chamber and oriented about the axis, wherein the cap is configured to receive a fuel injector and at least one glow plug, a tip at a downstream end of the combustion chamber, and a passage for pressurized oxygen containing gas passing through the cap from an exterior of the combustion chamber and in fluid communication with the combustion chamber. An embodiment of a method for starting a gas turbine engine is also disclosed.

BACKGROUND

The present disclosure relates to gas turbine engines and, moreparticular, to torch ignitors and methods suitable for use in torchignitors used in the combustor section of a gas turbine engine.

Torch ignitors can be used in lieu of spark ignitors to provide anignition source for combustors located in gas turbine engines. Torchignitors provide a flame to the combustion chamber of a gas turbineengine as an ignition source rather than the electric current providedby spark ignitors. Consequently, torch ignitors can provide a largertarget for fuel injectors within the combustor, allowing for utilizationof a greater range of fuel injector designs. Torch ignitors are intendedto remain active while the gas turbine is operating. There may beinstances where a torch ignitor can be useful for starting a gas turbineengine but where it is not easily feasible to start off of the gasturbine's compressor. In these instances it is advantageous to haveextra aid to starting the torch ignitor, which can then be used to startthe main combustor of the gas turbine engine.

SUMMARY

The present disclosure provides an embodiment of a torch ignitor systemfor a combustor of a gas turbine engine. The system includes a torchignitor, the torch ignitor including a torch wall oriented about anaxis, the torch wall having axially upstream and downstream endsdefining a flow direction through the combustion chamber, along theaxis. The torch ignitor also includes a cap defining the axiallyupstream end of the combustion chamber and oriented about the axis,wherein the cap is configured to receive a fuel injector and at leastone glow plug; a tip defining the axially downstream end of thecombustion chamber, and a passage for pressurized oxygen containing gaspassing through the cap from an exterior of the combustion chamber andin fluid communication with the combustion chamber.

The present disclosure additionally provides for a method that includesissuing liquid from a fuel injector into a combustion chamber of a torchignitor, issuing air assist from the fuel injector into the combustionchamber, issuing a separate stream of assist gas into the combustionchamber, igniting a fuel air mixture within the torch wall, and reducingthe separate stream of assist gas into the combustion chamber after thefuel air mixture is ignited.

BREIF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional side elevation view of an example of a torchignitor within the combustion section of a gas turbine engine.

FIG. 2 is a cross-sectional side elevation view of a cap of the torchignitor of FIG. 1, showing a gas assist path in accordance with at leastone aspect of this disclosure.

FIG. 3 is a cross-sectional view of a cap of a torch ignitor showinganother gas assist path in accordance with at least one aspect of thisdisclosure.

FIG. 4 is a cross-sectional view of a cap of a torch ignitor showing yeta another gas assist path accordance with at least one aspect of thisdisclosure.

FIG. 5 is a cross-sectional front view of a combustor looking upstreamshowing the torch ignitor of FIG. 1.

FIG. 6 is a block diagram of an example of a method for starting aturbine engine.

DETAILED DESCRIPTION

The present disclosure presents structures and methods for starting atorch ignitor suitable for igniting the combustor of a gas turbineengine.

The following are non-exclusive descriptions of possible embodiments ofthe present disclosure. At certain times, such as an emergency start,one time starts, or emergency altitude relights, a torch ignitor may beused to start the gas turbine engine, however these instances pose achallenge in starting the gas turbine engine if relying on the gasturbine engine compressor. Thus, it is advantageous to have additionalaid in starting the torch ignitor in order to start the gas turbineengine in such circumstances, such as an external source of compressedoxygen containing gas. The systems and methods disclosed herein allowfor starting a torch ignitor, and the main combustor of the gas turbine,under suboptimal conditions.

FIG. 1 is a cross sectional view of a torch ignitor 10 for a combustor24 of a gas turbine engine 100. The torch ignitor 10 can comprise atorch wall 16 (e.g. a combustion chamber for the torch ignitor 10)oriented about an axis A, and the torch wall 16 can have axiallyupstream and downstream ends 102, 104 defining a flow direction throughthe torch wall 16, along the axis A. A cap 34 (also shown in FIGS. 2-4)can define the axially upstream end of the torch wall 16 and can also beoriented about the axis A. The cap 34 may be separable from the torchwall 16, or may be formed integrally with the torch wall 16. In theexample shown in FIG. 1, the cap 34 can be configured to receive a fuelinjector 45, at least one glow plug 26, a tip 106 at a downstream end ofthe torch wall 16, and a passage 108 for pressurized oxygen containinggas (e.g. assist gas). In the passage 108, pressurized oxygen containinggas can pass through the cap 34 from an exterior of the torch wall 16where the pressurized oxygen containing gas can be in fluidcommunication with the torch wall 16. It is contemplated however thatassist gas may be issued through the both the fuel injector 45, featureswithin the cap section 34, and/or through the torch wall 16 to reach thecombustion chamber interior to the torch wall 16.

In operation, air enters the high pressure engine case 18 through inlet17 (e.g. from a main engine compressor). Torch ignitor 10 intakes highpressure air from the inside of high-pressure engine case 18. Thehigh-pressure air is channeled through cooling channels 28 to cool torchwall 16 before it is channeled into combustion chamber contained bytorch wall 16 to be used in combustion within torch ignitor 10 (forexample as shown in the enlarged view in FIG. 2).

The upstream end 102 of the torch ignitor 10 may be mounted to a highpressure engine case 18 (e.g. using mounting features within highpressure casing 18) while the tip 106 may be mounted to a main combustor24 within the high pressure engine case 18. The cap 34 may be mounted toupstream end 102 through aperture 132 in high pressure case 18 bythreads or other suitable means of retention. In this way, it ispossible for the main combustor 24 to be in fluid communication withcombustion products from within the torch wall 16, where the combustionproducts are produced from fuel and pressurized oxygen containing gasfrom sources outside the high pressure engine case 18. In operation, thecombustion products produced within the torch wall 16 can flow into thegas turbine combustor (e.g. main combustor 24), and eventually used tostart the turbine, as indicated by the “to turbine” arrow.

In embodiments, such as the example shown in FIG. 2, the torch ignitor10 can include a fuel injector seat 112 defined in the cap 34. The fuelinjector seat 112 can be configured to receive the fuel injector 45 andto provide a passage for injecting fuel, air, and/or assist gas from anexternal source 136 through the fuel injector 45 and into the torch wall16. It is also possible that the torch ignitor 10 can include at leastone glow plug seat 50 defined in the cap 34. The glow plug seat 50 canbe comprised of multiple components, such as a housing and sheath,however for the sake of simplicity, the structure will be hereinafterreferred to as the glow plug seat 50. The glow plug seat 50 can beconfigured to receive the glow plug 26 through the cap 34 where the glowplug 26 can extend through the cap 34 and through the torch wall 16 toinitiate ignition in fuel and air within the torch wall 16. It iscontemplated that the glow plug seat 50 can be a first glow plug seat 50a in a plurality of glow plug seats 50 a,b. As shown throughout theFIGS., glow plug seats 50 a,b are shown circumferentially spaced apartfrom one another around the axis A, such that an air passage 118 can bedefined in the cap 34 radially inward from the glow plug seats 50 a,b.The examples presented in the FIGS. and described herein provide for atleast one glow plug 26 and corresponding seat 50, for example, two glowplugs 26 a,b; however it should be appreciated by those skilled in theart that any suitable number of glow plugs 26 (and corresponding glowplug seats 50) can be employed.

In embodiments, such as the example shown in FIG. 2, the fuel injector45 can include a fuel injector seat 112, an air inlet 114, and aseparate fuel inlet 116. The cap 34 can include a separate air passage118 in fluid communication with the air inlet 114 of the fuel injector45 and a liquid fuel passage 120 in fluid communication with the fuelinlet 116 of the fuel injector 45. The cap 34 can also include aseparate gas passage 108, that can be in fluid communication with thefuel injector 45 for providing pressure-assist to the fuel injector 45from an external source 136.

The tip 106 of the torch ignitor 10 can be connected to the maincombustor 24 to discharge combustion products from within torch wall 16to the main combustor 24 for ignition of a fuel/air mixture in the maincombustor 24. The external source 136 of pressurized gas, external ofthe high pressure engine case 18, can be connected in fluidcommunication with the air passage 118 of the cap 34. Further, thesource of liquid fuel, external of the high pressure engine case 18, canalso be connected in fluid communication with the fuel injector 45 inthe cap 34. In addition, the external source 136 of pressurized oxygencontaining gas, can also be connected in fluid communication with thecap 34 to provide pressure-assisting gas from the source of pressurizedgas to initiate combustion within the torch wall 16.

In embodiments, the external source 136 can be an external source ofpressurized oxygen containing gas, for example. More particularly, theexternal source 136 can be a line run from an onboard compressed airsystem, or from a small pressurized compressed gas source (e.g. areplaceable and/or rechargeable bottle) which may activated by a valve(e.g. valve 134). It is contemplated that a rechargeable bottle may berecharged from the main engine compressor 17 at a high pressureoperation (i.e. takeoff condition) so that it is available for the nextstart or restart sequence. While not specifically described herein, itshould be appreciated by those skilled in the art that various methodsof activating the compressed gas supply to the torch ignitor can beused, for example a solenoid to rupture an aperture of the compressedgas tank, or a solenoid valve to open a compartment, among othersuitable methods.

Referring FIG. 2, the separate gas passage 108 of the cap 34 can be influid communication with the air inlet 114 of the fuel injector 45 sothat gas from both the gas passage 108 of the cap 34 and air from theair passage 118 can both feed into an inlet 124 of the fuel injector 45.For example, compressed gas from an external source 136 can be inserteddirectly into the stream of air from air passage 118, through separategas passage 108. The compressed oxygen containing gas can then be usedfor atomizing fuel, and as the compressed oxygen containing gas source(e.g. from the main engine compressor 17) becomes adequate, thecompressed oxygen containing gas supply can be reduced and/or turned offvia a valve 134. When gas from the compressed gas source is also usedfor atomization, such as shown in FIG. 2 for example, air from the mainengine compressor 17 can then take over operation of the compressed gascircuit once the gas turbine engine 100 is started and the main enginecompressor 17 is adequate.

Referring to FIG. 3, the separate gas passage 108 of the cap 34 can beconnected to the fuel injector 45 at an assist gas port 126 of the fuelinjector 45. The assist gas port 126 and separate gas passage 108 can bea separate gas passage 124 of the fuel injector 45 so that air from theair passage 118 of the cap 34 remains separate from gas in the separategas passage 108 of the cap 34 upstream of the fuel injector 45. Here,the compressed oxygen containing gas can be injected into the fuelinjector inlet 114 through a circuit (e.g. separate gas passage 108)directly into the fuel injector 45, where the separate gas passage 108is separate from the compressed air used for atomization (e.g. the airflowing through the air passage 118). As shown in both examples in FIGS.2-3, the separate gas passage 108 through the cap 34 can be at leastpartially within the air passage 118 of the cap 34.

In further embodiments, such as the example shown in FIG. 4, the cap 34can also include a separate gas passage 108, where the separate gaspassage 108 through the cap 34 can be lateral from the glow plug seats50 a,b relative to the axis A. As such, the separate gas passage 108 canbe in fluid communication with an outlet 128 in the torch wall 16, wherethe outlet is downstream of the fuel injector exit 122. For example,compressed oxygen containing gas can be injected into the torch ignitortorch wall 16 via separate gas passage 108. In such a configuration, thecompressed oxygen containing gas is may not be used for atomization ofthe fuel but may provide sufficient compressed oxygen containing gas forreacting with fuel within the torch wall 16.

It is possible that each torch ignitor 10 includes its own fuel injector45, and that the main combustor 24 includes a plurality of main fuelinjectors 145. It is also contemplated that the system 1 can include aplurality of torch ignitors 10 spaced between respective main fuelinjectors 145 such as shown in FIG. 5. For each torch ignitor 10, thetorch wall 16 can be outside of the main combustor 24, while none of themain fuel injectors 145 includes a combustion chamber outside of themain combustor 24.

In embodiments, the torch ignitor 10 can include control valve 134 inline between the source 136 of pressurized oxygen containing gas and thecap 34 for controlling supply from the source 136 of pressurized oxygencontaining gas to the cap 34. The source 136 of oxygen containing gascan be any of a source of oxygen or air, for example, roughly 21%oxygen, 79% nitrogen for an air source, or 100% oxygen for an oxygensource, however as appreciated by those skilled in the art, any suitableoxygen containing gas or combination thereof can be used.

FIG. 6 shows a block diagram of a method 200 for starting a gas turbineengine 100, using a torch ignitor system as described above. At box 202,the method 200 can include issuing liquid (e.g. liquid fuel from theliquid fuel passage 116) from a fuel injector 45 within torch wall 16 ofa torch ignitor 10. Next, at box 204, the method 200 can include issuingair (e.g. air from the air inlet passage 118) from the fuel injector 45into the torch wall 16. At box 206, the method 200 can include issuing aseparate stream of assist gas (e.g. assist gas from separate gas passage108) into the torch wall 16. The method 200 can include, as shown at box208, igniting a fuel air mixture within the torch wall 16, and at box202, using flame issued from the torch wall 16 to ignite a fuel/airmixture in a combustor 24 of a gas turbine engine 100. The method 200can include issuing the ignited combustion products from the combustionchamber into a main combustor to ignite a fuel/air mixture in a maincombustor of a gas turbine engine, at box 210. At box 212, using flameissued from the torch wall 16 can also include relighting the gasturbine engine after in-flight flame out, for example an emergencyrelight at altitude. At box 214, the method 200 can include reducing theseparate stream of assist gas into the torch wall 16 after the fuel airmixture is ignited. It is contemplated that reducing the separate streamof assist gas (e.g. box 214) can includes completely deactivating theseparate stream of assist gas, as shown at box 216, when a supply ofassist gas is no longer needed. The compressed oxygen containing gas isonly required to start the reaction, and can therefore be stopped oncethe reaction is sustained.

Discussion of Possible Embodiments

The following are non-exclusive descriptions of possible embodiments ofthe present disclosure.

An embodiment of a torch ignitor system for combustor of a gas turbineengine includes a torch ignitor, the torch ignitor having a combustionchamber oriented about an axis, the combustion chamber having axiallyupstream and downstream ends defining a flow direction through thecombustion chamber, along the axis. The torch ignitor system alsoincludes a cap defining the axially upstream end of the combustionchamber and oriented about the axis, wherein the cap is configured toreceive a fuel injector and at least one glow plug, a tip at adownstream end of the combustion chamber, and a passage for pressurizedoxygen containing gas passing through the cap from an exterior of thecombustion chamber and in fluid communication with the combustionchamber.

The system of the preceding paragraph can optionally include,additionally and/or alternatively, any one or more of the followingfeatures, configurations and/or additional components:

A torch ignitor system for combustor of a gas turbine engine accordingto an exemplary embodiment of this disclosure, among other possiblethings, includes the upstream end mounted to a high pressure engine caseand the tip is mounted to a main combustor within the high pressure casefor fluid communication combustion products into the combustor.

A further embodiment of the foregoing system can further comprise, afuel injector seat defined in the cap configured to receive the fuelinjector and provide passage for injecting fuel and gas from an externalsource through the fuel injector into the combustion chamber, and atleast one glow plug seat defined in the cap configured to receive arespective glow plug of the at least one glow plug through the cap andinto the combustion chamber for initiating ignition in fuel and air inthe combustion chamber.

A further embodiment of any of the foregoing systems, wherein the fuelinjector includes an air inlet and a separate fuel inlet, wherein thecap includes an air passage in fluid communication with the air inlet ofthe fuel injector and a liquid fuel passage in fluid communication withthe fuel inlet of the fuel injector, and wherein the cap includes aseparate gas passage therethrough, wherein the separate gas passage isin fluid communication with the fuel injector for providingpressure-assist to the fuel nozzle from an external source ofpressurized oxygen containing gas.

A further embodiment of any of the foregoing systems, wherein theseparate gas passage of the cap is in fluid communication with the airinlet of the fuel injector so that gas from both the gas passage of thecap and from the air passage both feed into the inlet of the fuelinjector.

A further embodiment of any of the foregoing systems, wherein theseparate gas passage of the cap is connected to the fuel injector at anassist gas port of the fuel injector that is separate from the inlet ofthe fuel injector keeping air from the air passage of the cap separatefrom gas in the separate gas passage of the air cap upstream of the fuelinjector.

A further embodiment of any of the foregoing systems, wherein the fuelinjector includes an air inlet and a separate fuel inlet, wherein thecap includes an air passage in fluid communication with the air inlet ofthe fuel injector and a liquid fuel passage in fluid communication withthe fuel inlet of the fuel injector, and wherein the cap includes aseparate gas passage therethrough with an outlet in the combustionchamber downstream of a fuel nozzle.

A further embodiment of any of the foregoing systems, wherein the atleast one glow plug seat is a first glow plug seat in a plurality ofglow plug seats defined through the cap, wherein the glow plug seats arecircumferentially spaced apart from one another around the axis, whereinan air passage in fluid communication with the air inlet of the fuelinjector is defined in the cap radially inward from the glow plug seats.

A further embodiment of any of the foregoing systems, wherein the capincludes a separate gas passage therethrough that is at least partiallywithin the air passage of the cap.

A further embodiment of any of the foregoing systems, wherein the capincludes a separate gas passage therethrough that is lateral from theglow plug seats relative to the axis.

An embodiment of a torch ignitor system for combustor of a gas turbineengine can further comprise a high pressure engine case, wherein the capis mounted to an opening through the high pressure engine case, a maincombustor, wherein the tip is connected to discharge combustion productsinto the main combustor, a source of pressurized air external of thehigh pressure engine case connected in fluid communication with an airpassage of the air cap, a source of liquid fuel external of the highpressure case connected in fluid communication with a fuel injector inthe cap, and a source of pressurized oxygen containing gas external ofthe high pressure engine case connected in fluid communication with thecap.

A further embodiment of any of the foregoing systems can furthercomprise a plurality of main fuel injectors mounted to the maincombustor, wherein the torch combustion chamber is outside of the maincombustor, and wherein none of the main fuel injectors includes acombustion chamber outside of the main combustor.

A further embodiment of any of the foregoing systems can furthercomprise a control valve in line between the source of pressurizedoxygen containing gas and the cap wherein the control valve isconfigured to control supply from the source of pressurized oxygencontaining gas to the cap.

A further embodiment of any of the foregoing systems, wherein the sourceof oxygen containing gas is a source of oxygen.

A further embodiment of any of the foregoing systems, wherein the sourceof oxygen containing gas is source of air.

An embodiment of a method includes issuing liquid from a fuel injectorinto a combustion chamber of a torch ignitor, issuing air from the fuelinjector into the combustion chamber, issuing a separate stream ofassist gas into the combustion chamber, igniting a fuel air mixturewithin the combustion chamber, and reducing the separate stream ofassist gas into the combustion chamber after the fuel air mixture isignited.

The method of the preceding paragraph can optionally include using flameissued from the combustion chamber to ignite a fuel/air mixture in amain combustor of a gas turbine engine.

A further embodiment of any of the foregoing methods, wherein usingflame issued from the combustion chamber includes relighting the gasturbine engine after in-flight flame out.

A further embodiment of any of the foregoing methods, wherein reducingthe separate stream of assist gas includes completely deactivating theseparate stream of assist gas.

A further embodiment of any of the foregoing methods, wherein the assistgas includes at least one of air and/or oxygen.

While the invention has been described with reference to an exemplaryembodiment(s), it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment(s) disclosed, but that theinvention will include all embodiments falling within the scope of theappended claims.

1. A torch ignitor system for a combustor of a gas turbine engine,comprises: a torch ignitor comprising: a combustion chamber orientedabout an axis, the combustion chamber having axially upstream anddownstream ends defining a flow direction through the combustionchamber, along the axis; a cap defining the axially upstream end of thecombustion chamber and oriented about the axis, wherein the cap isconfigured to receive a fuel injector and at least one glow plug; a tipat the axially downstream end of the combustion chamber; a passage forpressurized oxygen containing gas passing through the cap from anexterior of the combustion chamber and in fluid communication with thecombustion chamber; a fuel injector in the cap that includes an airinlet and a separate fuel inlet, wherein the cap includes an air passagein fluid communication with the air inlet of the fuel injector and aliquid fuel passage in fluid communication with the fuel inlet of thefuel injector, and wherein the cap includes a separate gas passagetherethrough; a high pressure engine case, wherein the cap is mounted toan opening through the high pressure engine case; a main combustor,wherein the tip is connected to discharge combustion products into themain combustor to ignite a fuel/air mixture in the main combustor; asource of pressurized air external of the high pressure engine caseconnected in fluid communication with an air passage of the cap; asource of liquid fuel external of the high pressure engine caseconnected in fluid communication with a fuel injector in the cap; and asource of pressurized oxygen containing gas external of the highpressure engine case connected in fluid communication with the cap. 2.The torch ignitor system as recited in claim 1, wherein the upstream endis mounted to a high pressure engine case and the tip is mounted to themain combustor within the high pressure engine case for fluidcommunication of combustion products into the main combustor.
 3. Thetorch ignitor system as recited in claim 1, further comprising: a fuelinjector seat defined in the cap configured to receive the fuel injectorand provide passage for injecting fuel and gas from the external sourcethrough the fuel injector into the combustion chamber; and at least oneglow plug seat defined in the cap configured to receive a respectiveglow plug of the at least one glow plug through the cap and into thecombustion chamber.
 4. The torch ignitor system as recited in claim 3,wherein the separate gas passage is in fluid communication with the fuelinjector for providing pressure-assist to the fuel injector from anexternal source of pressurized oxygen containing gas.
 5. The torchignitor system as recited in claim 4, wherein the separate gas passageof the cap is in fluid communication with the air inlet of the fuelinjector so that the gas from both the separate gas passage of the capand from the air passage both feed into the inlet of the fuel injector.6-7 .
 8. The torch ignitor system as recited in claim 3, wherein the atleast one glow plug seat is a first glow plug seat in a plurality ofglow plug seats defined through the cap, wherein the glow plug seats arecircumferentially spaced apart from one another around the axis, whereinan air passage in fluid communication with the air inlet of the fuelinjector is defined in the cap radially inward from the glow plug seats.9. The torch ignitor system as recited in claim 8, wherein the capincludes a separate air passage therethrough that is at least partiallywithin the air passage of the cap.
 10. The torch ignitor system asrecited in claim 8, wherein the cap includes a separate air passagetherethrough that is lateral from the plurality of glow plug seatsrelative to the axis.
 11. (canceled)
 12. The torch ignitor system asrecited in claim 1, further comprising a plurality of main fuelinjectors mounted to the main combustor, wherein the combustion chamberof the torch ignitor is outside of the main combustor, and wherein noneof the main fuel injectors includes a combustion chamber outside of themain combustor.
 13. The torch ignitor system as recited in claim 1,further comprising a control valve in line between the source ofpressurized oxygen containing gas and the cap, wherein the control valveis configured to control supply from the source of pressurized oxygencontaining gas to the cap.
 14. The torch ignitor system as recited inclaim 1, wherein the source of oxygen containing gas is a source ofoxygen.
 15. The torch ignitor system as recited in claim 1, wherein thesource of oxygen containing gas is source of air. 16-20.